Conversion of naphthenes to higher aromatics



y 17, 1956 R. w. BLUE ETAL CONVERSION OF NAPHTHENES T0 HIGHER AROMATICSFiled July 11, 1952 "/FRACTIONATOR REACTOR HEATER CONDENSER ISOBUTYLENE,4 TRIMETHYL BENZENE IN V EN TORS R.W. BLUE BY V.C.F.HOLM

A TTOR/VEYS CONVERSION OF NAPHTHENES TO HIGHER AROMATICS Richard W. Blueand Vernon C. F. Holm, Bartlesviile,

Okla, assignors to Phillips Petroleum Company, a corporatton of DelawareApplication July 11, 1952, Serial No. 298,402

14 Claims. (Cl. 260-668) This invention relates to a process for theconversion of naphthenes to aromatics containing a greater number ofcarbon atoms per molecule than the original naphthene. In a morespecific aspect this invention relates to a process for the productionof aromatic hydrocarbons from naphthenic and olefinic hydrocarbons by ahydrogen transfer process whereby the aromatics are recovered bydistillation. In another specific aspect this invention relates to amethod for producing 1,2,4-trimethyl benzene.

Naphthenic straight-run gasoline fractions, have in general, relativelypoor anti-knock properties, and are therefore not well suited forblending in gasolines in which a high octane rating is desired. Aromatichydrocarbons, however, impart high octane rating to motor fuels and arein great demand. The demand for aromatic hydrocarbons for use inchemical industries is so great that it has become impractical to addaromatics to motor fuels solely for their octane rating characteristics.Thus a process for producing aromatics from naphthenes is verydesirable.

Each of the following objects will be attained by the aspects of thisinvention.

it is an object of this invention to provide a process for theproduction of alkyl aromatics from a mixture of olefins and naphthenes.

Another object is to provide a process for improving the octane ratingof a motor fuel containing olefins and naphthenes.

Another object is to provide a process for converting naphthenes intoaromatics having a greater number of carbon atoms per molecule than theoriginal naphthene.

Another object is to provide a method for the production of aromaticswherein the aromatics produced can be removed from the reactants bydistillation.

Another object is to provide a method for producing 1,2,4-trimethy1benzene.

Another object is to provide a novel hydrogen transfer process.

Other objects and advantages will be apparent to one skilled in the artupon reading this specification and the attached drawing.

We have discovered that a hydrocarbon mixture containing olefins andnaphthenes can be subjected to hydrogen transfer reaction conditions inthe presence of a catalyst selected from the group consisting ofaluminaaluminum fluoride, silica-magnesia, silica-boria, andsilicaalumina, and the catalyst bases silica-alumina and silica,activated by oxides of the metals of groups 3-H and 4-13 of the periodictable of elements with the result that aromatic hydrocarbons areproduced having a greater number of carbon atoms per molecule thancontained in the original naphthene and the aromatics can be recoveredby distillation.

The metals of groups 3-B and 4-3 of the periodic table of elements arethose set forth in Langes Handbok of Chemistry, 5th edition, 1944, atpages 54 and 55. Therein the metals of group 3-13 are stated to bescandium, yttrium, and the rare earth metals and the metals of groupnited States Patent 0 4-B are stated to be titanium, zirconium, hafniumand thorium. In the specification and in the claims the metals of groups3B and 4-13 of the periodic table of elements are the metals as setforth above.

In accordance with this invention olefinic hydrocarbons are reacted withnaphthenic hydrocarbons in the presence of a catalyst selected from thegroup consisting of aluminaaluminum fluoride, silica-magnesia,silica-boria, silicaalumina and the catalyst bases silica-alumina andsilica, activated by oxides of the metals of groups 3-B and 4B of theperiodic table of elements and under hydrogen transfer conditions so asto produce aromatic hydrocarbons having a higher molecular weight thanthe naphthene and the aromatic hydrocarbons produced are recovered asthe bottom product in a distillation step.

This process provides a novel method for the production of1,2,4-trimethyl benzene.

Although naphthenes and olefins in general can be used in this processwe prefer to use naphthenic hydrocarbons having from 5 to 6 carbon atomsin the ring and olefins having from 3 to 6 carbon atoms. isobutene isthe olefin most generally preferred. When hydrocarbon charge stocks inour preferred range are used in our process the aromatics produced canbe separated from the unreacted charge stock by distillation.

Naphthenes in our preferred range include methyl cyclopentane, dimethylcyclopentane, trimethyl cyclopentane, ethyl cyclopentane, methyl-ethylcyclopentane, isopropyl cyclonpentane, n-propyl cyclopentane,cyclohexane, methyl cyclohexane, dimethyl cyclohexane, trimethylcyclohexane, ethyl cyclohexane, methyl-ethyl cyclohexane, isopropylcyclohexane, and n-propyl cyclohexane.

Olefins in our preferred range include propylene, butenes, isobutene,pentene, isopentenes, hexene and isohexenes.

Relatively pure compounds such as methylcyclohexane and isobutene can betreated with this process as desired. This process can also be adaptedto the treatment of olefinic hydrocarbon mixtures and naphthenicstraight-run gasoline fractions to produce a hydrocarbon mixturecontaining aromatics. Naphthenic fractions containing at least 20 percent by volume of naphthenes and olefinic hydrocarbon mixturescontaining at least 20 per cent by volume of olefins are preferredcharge stocks for this reaction.

The ratio of naphthenes to olefins for this reaction is dependent uponthe degree of unsaturation of the olefinic charge stock and theavailable hydrogen in the naphthene. The ratio of naphthenes to olefinsin the charge can suitably range from 1:1 to 1:10, with the preferrednaphthene to olefin ratio being 1:2 to 1:4.

The hydrogen transfer reaction with methylcyclohexane yields a largeproportion of aromatic products having a higher boiling point thantoluene. Cyclohexane and methyl-cyclopentane give rise to a similardistribution of products.

The catalysts which can be used for this hydrogen transfer reactioninclude silica-alumina, silica-zirconia, silicaalumina-zirconia,silica-boria, silica-scandia, silica-alumina-scandia, silica-yttria,silica-alumina-yttria, silica-praseodymia, silica-alumina-praseodymia,silica-neodymi, silica-alumina-neodymia, silica-illinia,silica-alumina-illinia, silica-samaria, silica-alumina-samaria,silica-europia, silicaalumina-europia, silica-gadolinia,silica-alumina-gadolinia, silica-terbia, silica-altnnina-terbia,silica-dysprosia, silicaalumina-dysprosia, silica-holmia,si'licaalumina-holmia, silica-erbia, silica-alurnina-erbia,silica-thulia, silica-alumina-thulia, silica-ytterbia,silica-alumina-ytterbia, silicalutecia, silica-alumina-lutecia,silica-titania, silica-aluminatitania, silica-hafnia,silica-alumina-hafnia, silica-thon'a, silica-alumina-thoria,silica-magnesia and alumina-aluminum fluoride. Alumina-molybdena andalumina-chromia catalysts are not desirable catalysts for this hydrogentransfer reaction. Using the catalyst from the above group thetemperatures for the reaction will usually range from 300 to 500 C. witha preferred range of from 350 to 475 C. The pressure should besubstantially atmospheric with enough differential to cause the desiredflow. Thus the pressure should be from 1 to 2 atmospheres and preferably1 to 1 atmospheres. There is no free hydrogen conearned or produced inthis hydrogen transfer reaction. Feed charge rates by weight of totalcharge stock per weight of catalyst per hour should be in the range of0.1 to 10 and preferably in the range 0.5 to 5. These charge rates areindicated where a fixed bed catalyst is employed. It the hydrogentransfer reaction is to be effected in a fluid catalyst bed process,catalystzoil ratios ranging from 1:1 to 30:1 by weight will usually besatisfactory. The preferred range is :1 to 15:1.

The invention is illustrated diagrammatically in the attached drawing.Reference is made to the drawing wherein a naphthenic hydrocarbon, forexample methylcyclohexane, i admitted through line 1 and an olefin, forexample isobutylene, is admitted through line 2. These hydrocarbons areinitially heated in heat-exchanger 3 and then heated to reactiontemperature in heater 4 and passed into reaction 5 which contains acatalyst selected from the designated group. The efiluent leaves thereactor through line 6, gives up heat to heat-exchanger 3 and isadmitted an an intermediate tray of a conventional bubble capfractionator 7. Unreacted hydrocarbons and low boiling aromatichydrocarbons are passed overhead from fractionator 7 through line 11 andcooler 12 through condenser 13. Non-condensed gases are vented fromcondenser 13 from line 14. Condensed liquid hydrocarbons are passed fromcondenser 13 through line 15, heat-exchanger 3, heater 4 and returned toreactor 5 with the fresh hydrocarbon feed.

High boiling alkyl aromatics produced in the process, for example,1,2,4-trimethylbenzene, are removed as a bottoms product fromfractionator 7 through lines 8 and 10. If additional heat is required infractionator 7 it is supplied in reboiler 9.

The following examples illustrate the advantages of this invention butare not intended to limit the invention.

EXAMPLE I Four minute runs reacting one part by weight ofmethylcyclohexane with 1.29 parts by weight of isobutene were made at450 C. and atmospheric pressure using 100 ml. of syntheticsilica-alumina bead-type catalyst crushed and sized to 40-60 mesh (U. S.Standard) with liquid hourly space velocities of 1.3. The liquid productwas fractionated and the fractions were analyzed by the infra-redabsorption method. The aromatic composition The total aromatics by thesilica gel method was 25 per cent.

EXAMPLE 11 Various combinations of naphthenes and olefins were run overthe catalyst of Example I and under conditions similar to those inExample I. The liquid products were not fractionated but were analyzedby the infra-red absorption method which showed a product distributionsimilar to that reported in Example I.

Reasonable variations and modifications are possible within the scope ofthe disclosure and drawing of this invention, the essence of which isthat a naphthene can be converted into an aromatic having a greaternumber of carbon atoms than the original naphthene by contacting thenaphthene with an olefin, under hydrogen transfer conditions, and in thepresence of a catalyst selected from the group consisting ofalumina-aluminum fluoride, silicaboria, silica-alumina, silica magnesia,and the catalyst bases silica-alumina and silica activated by the oxidesof the metals of groups 3-8 and 4B of the periodic table of elements asshown in Langes Handbook of Chemistry, 1944.

We claim:

1. The process for producing aromatic hydrocarbons by convertingnaphthene hydrocarbons into aromatic hydrocarbons having a greaternumber of carbon atoms than the naphthene hydrocarbons which comprisesreacting a hydrocarbon mixture comprising naphthenic hydrocar benscontaining from 5 to 6 carbon atoms in the ring and a minimum of 6carbon atoms in the molecule and olefinic hydrocarbons containing 3 to 6carbon atoms as the sole reactants and having a naphthene to olefinratio in the range 1:1 to 1:10, in the presence of a catalyst selectedfrom the group consisting of alumina-aluminum fluoride, silica-boria,silica-alumina, silica-magnesia, and the catalyst bases silica-aluminaand silica activated by oxides of the metals of groups 3-B and 4-3 ofthe periodic table of elements at substantially atmospheric pressure, atemperature in the range 300 to 500 C., and a feed rate in the range of0.1 to 10 by weight of feed catalyst per hour; separating the resultinghydrocarbon mixture in a distillation step; and recovering an aromatichydrocarbon having a greater number of carbon atoms than said naphthenichydrocarbon as a product of the process.

2. The process of claim 1 wherein the catalyst is silicaalumina.

3. The process of claim 1 wherein the catalyst issilica-alumina-zirconia.

4. The process of claim 1 wherein the catalyst is silicazirconia.

5. The process of claim 1 wherein the catalyst is silica-titania.

6. The process of claim 1 wherein the catalyst is silicathoria.

7. A process for producing aromatic hydrocarbons by converting naphthenehydrocarbons into aromatic hydrocarbons having a greater number ofcarbon atoms than the naphthene hydrocarbon which comprises reactingsaid naphthene hydrocarbon containing from 5 to 6 carbon atoms in thering and a minimum of 6 carbon atoms in the molecule with an olefinhydrocarbon containing from 3 to 6 carbon atoms as the sole reactants inthe presence of a solid catalyst selected from the group consisting ofalumina-aluminum fluoride, silica-boria, silica-alumina,silica-magnesia, and the catalyst bases silica alumina and silicaactivated by oxides of the metals of groups 3B and 4B of the periodictable of elements at substantially atmospheric pressure and at atemperature in the range 300 to 500 C.; separating the resultingmixture; and recovering aromatic hydrocarbons having a greater number ofcarbon atoms than the naphthene hydrocarbons as a product of theprocess.

8. A process for producing 1,2,4-trimethyl benzene which comprisesreacting a naphthenic hydrocarbon having from 56 carbon atoms in thering and a minimum of 6 carbon atoms in the molecule with an olefinhaving from 3-6 carbon atoms as the sole reactants in the presence of acatalyst selected from the group consisting of alumina-aluminumfluoride, silica-boria, silica-alumina, silica-magnesia, and thecatalyst bases silica-alumina and silica activated by oxides of themetals of groups 3-H and 4B of the periodic table of elements atsubstantially atmospheric pressure and a temperature in the range 350 to475 C.; separating the resulting hydrocarbon mixture in a distillationstep; and recovering 1,2,4-trimethylbenzene as the kettle product ofsaid distillation step.

9. A process for producing 1,2,4-trimethylbenzene which comprisescontacting a hydrocarbon stream comprising a naphthenic hydrocarboncontaining from to 6 carbon atoms in the ring and a minimum of 6 carbonatoms in the molecule with a hydrocarbon stream comprising an olefinichydrocarbon containing from 3 to 6 carbon atoms as the sole reactantsand in a naphthene to olefin ratio in the range of 1:1 to 1:10 and witha catalyst selected from the group consisting of alumina-aluminumfluoride, silica-boria, silica-alumina, silica-magnesia and the catalystbases silica-alumina and silica activated by oxides of the metals ofgroups 3B and 4-B of the periodic table of elements, a pressure in therange of l to 2 atmospheres, at a temperature in the range 300 to 500C., and a feed rate in the range 0.1 to parts by weight of saidhydrocarbons per part of catalyst per hour; separating the resultinghydrocarbon mixture in a distillation step; and recovering1,2,4-trimethylbenzene as the kettle product of the distillation step asa product of the process.

10. The process of claim 8 wherein the catalyst is silica-alumina, thetemperature is in the range 350 to 475 C., and the feed rate is in therange 0.5 to 5 parts by weight of hydrocarbon per part of catalyst perhour.

11. A process for producing 1,2,4-trimethylbenzene which comprisesreacting methylcyclohexane with isobutene as the sole reactants in thepresence of a catalyst selected from the group consisting ofalumina-aluminum fluoride, silica-boria, silica-alumina,silica-magnesia, and the catalyst bases silica-alumina and silicaactivated by an oxide of the metals of groups 3B and 4B of the periodictable of elements at substantially atmospheric pressure and atemperature in the range 350-475 C.; separating the resultinghydrocarbon mixture in a distillation step; and recovering1,2,4-trimethylbenzene as the kettle product of said distillation step.

12. A process for producing 1,2,4-trirnethylbenzene which comprisesreacting cyclohexane with isobutene as the sole reactants in thepresence of a catalyst selected from the group consisting ofalumina-aluminum fluoride,

silica-boria, silica-alumina, silica-magnesia, and the catalyst basessilica-alumina and silica activated by an oxide of the metals of groups3B and 4-B of the periodic table of elements at substantiallyatmospheric pressure and a temperature in the range 350475 C.;separating the resulting hydrocarbon mixture in a distillation step; andrecovering 1,2,4-trimethylbenzene as the kettle product of saiddistillation step.

13. A process for producing 1,2,4-trimethylbenzene which comprisesreacting methylcyclopentane with propylene as the sole reactants in thepresence of a catalyst selected from the group consisting ofalumina-aluminum fluoride, silica-boria, silica-alumina,silica-magnesia, and the catalyst bases silica-alumina and silicaactivated by an oxide of the metals of groups 3-B and 4B of the periodictable of elements at substantially atmospheric pressure and atemperature in the range 350-475 C.; separating the resultinghydrocarbon mixture in a distillation step; and recovering1,2,4-trimethylbenzene as the kettle product of said distillation step.

14. A process for producing 1,2,4-trirnethylbenzene which comprisesreacting methylcyclohexane with propylene as the sole reactants in thepresence of a catalyst selected from the group consisting ofalumina-aluminum fluoride, silica-boria, silica-alumina,silica-magnesia, and the catalyst bases silica-alumina and silicaactivated by an oxide of the metals of groups 3-B and 4B of the perodictable of elements at substantially atmospheric pressure and atemperature in the range 350475 C.; separating the resulting hydrocarbonmixture in a distillation step; and recovering 1,2,4-trimethylbenzene asthe kettle product of said distillation step.

References Cited in the file of this patent UNITED STATES PATENTS2,242,960 Sachanen et al May 20, 1941 2,283,854 Friedman et al. May 19,1942 2,479,110 Haensel Aug. 16, 1949 2,495,648 Voge et al. Jan. 24, 19532,626,286 Voorhies et al. Jan. 20, 1953

1. THE PROCESS FOR PRODUCING AROMATIC HYDROCARBONS BY CONVERTING NAPHTHENE HYDROCARBONS INTO AROMATIC HYDROCARBONS HAVING A GREATER NUMBER OF CARBON ATOMS THAN THE NAPHTHENE HYDROCARBONS WHICH COMPRISES REACTING A HYDROCARBON MIXTURE COMPRISING NAPHTHENIC HYDROCARBONS CONTAINING FROM 5 TO 6 CARBON ATOMS IN THE RING AND A MINIMUM OF 6 CARBON ATOMS IN THE MOLECULE AND OLEFINIC HYDROCARBONS CONTAINING 3 TO 6 CARBON ATOMS AS THE SOLE REACTANTS AND HAVING A NAPHTHENE TO OLEFIN RATIO IN THE RANGE 1:1 TO 1:10, IN THE PRESENCE OF A CATALYST SELECTED FROM THE GROUP CONSISTING OF ALUMINA-ALUMINUM FLUORIDE, SILICA-BORIA, SILICA-ALUMINA, SILICA-MAGNESIA, AND THE CATALYST BASES SILICA-ALUMINA AND SILICA ACTIVATED BY OXIDES OF THE METALS OF GROUPS 3-B AND 4-B OF THE PERIODIC TABLE OF ELEMENTS AT SUBSTANTIALLY ATMOSPHERIC PRESSURE, A TEMPERATURE IN THE RANGE 300 TO 500* C., AND A FEED RATE IN THE RANGE OF 0.1 TO 10 BY WEIGHT OF FEED CATALYST PER HOUR; SEPARATING THE RESULTING HYDROCARBON MIXTURE IN A DISTILLATION STEP; AND RECOVERING AN AROMATIC HYDROCARBON HAVING A GREATER NUMBER OF CARBON ATOMS THAN SAID NAPHTHENIC HYDROCARBON AS A PRODUCT OF THE PROCESS. 